FIG. 1 is a cross-sectional view of a prior art torque converter, shown secured to an engine of a motor vehicle. Generally, the three main components of the torque converter are the pump 37, turbine 38, and stator 39. The torque converter becomes a sealed chamber when the pump is welded to cover 11. Cover 11 includes pilot 54 extending axially from the cover. Pilot 54 is concentric with cover 11 and connected to the cover by weld 56. Pilot 54 is used to align the cover lugs or studs with the engine crankshaft or flexplate during installation of the torque converter.
Cover 11 is connected to flexplate 41 which is, in turn, bolted to crankshaft 42 of engine 7. The cover can be connected to the flexplate using lugs or studs welded to the cover. The welded connection between the pump and cover transmits engine torque to the pump. Therefore, the pump always rotates at engine speed. The function of the pump is to use this rotational motion to propel the fluid radially outward and axially towards the turbine. Therefore, the pump is a centrifugal pump propelling fluid from a small radial inlet to a large radial outlet, increasing the energy in the fluid. Pressure to engage transmission clutches and the torque converter clutch is supplied by an additional pump in the transmission that is driven by the pump hub.
The pilot functions to align the torque converter assembly with the flexplate so that the torque converter assembly may be rotationally attached to the engine. By align, we mean that the pilot is manufactured to specific tolerances in order to fit within a recess in the crankshaft such that the torque converter lugs or studs properly align with the flexplate. Once the lugs or studs are attached to the flexplate, the pilot does not carry much load.
Traditionally, torque converter pilots were either welded then machined or formed integral to the cover in a stamping process. The first procedure, welding then machining, required forging a pilot, machining the pilot to specific dimensions, welding the pilot to the cover, and again machining the pilot to compensate for the distortion caused by the welding process. Although this process provides the ease of reduced stamping operations, the multiple machining operations and forging of the pilot are both costly and time consuming.
The second procedure, stamping the pilot, required an increase in the process steps for production of the cover. To produce a torque converter cover, a piece of sheet metal is stamped by presses in multiple stations until the proper form is realized. However, stamping the cover pilot requires additional stations in the press, additional press cycles, or potentially retooling with more complex dies or longer stroke presses. By this we mean that the stamping process may need to have a large number of dies to form the pilot or special presses due to the additional axial length needed to stamp the pilot.
Therefore, there is a long-felt need to provide a torque converter cover with a pilot which is easy to manufacture and cost efficient, yet is still able to properly align the torque converter with the flexplate during installation.